Subaru Legacy IV (2008 year). Manual - part 910

ABS(diag)-39

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

Step

Check

Yes

WHETHER A WHEEL TURNED FREELY OR
NOT.
Check if the wheels have been turned freely for
one minute or more, such as when the vehicle is
jacked-up, under full-lock cornering or when the
wheels are not in contact with road surface.

Did the wheels turn freely?

ABS is normal.
Clear the memory.

NOTE:
This diagnostic
trouble code may
sometimes occur if
the wheels turn
freely for a long
time, for example
when the vehicle is
towed or jacked-
up, or when steer-
ing wheel is contin-
uously turned all
the way.

Go to step 2.

CHECK TIRE SPECIFICATIONS.
Turn the ignition switch to OFF.

Are the tire specifications cor-
rect?

Go to step 3.

Replace the tire.

CHECK WEAR OF TIRE.

Is the tire worn excessively?

Replace the tire.

Go to step 4.

CHECK TIRE INFLATION PRESSURE.

Is the tire pressure correct?

Go to step 5.

Adjust the tire
pressure.

CHECK INSTALLATION OF ABS WHEEL
SPEED SENSOR.

Are the ABS wheel speed sen-
sor installation bolts tightened
7.5 N·m (0.76 kgf-m, 5.5 ft-lb)?
(For four wheels)

Go to step 6.

Tighten the ABS
wheel speed sen-
sor installation
bolts.

CHECK ABS WHEEL SPEED SENSOR SIG-
NAL.
1) Install the ABS wheel speed sensor.
2) Prepare an oscilloscope.
3) Check the ABS wheel speed sensor. <Ref.
to ABS-14, ABS WHEEL SPEED SENSOR,
INSPECTION, Front ABS Wheel Speed Sen-
sor.>

Does the oscilloscope indicate
the waveform pattern like
shown in the figure when the
tire is slowly turned? Does the
oscilloscope indication repeat
the waveform pattern like
shown in the figure when the
tire is slowly turned in equal
speed for one rotation or more?

Go to step 8.

Go to step 7.

CHECK ABS WHEEL SPEED SENSOR OR
MAGNETIC ENCODER.

Are there foreign matter, break-
age or damage at the tip of ABS
wheel speed sensor or mag-
netic encoder?

Remove dirt thor-
oughly. Also
replace the ABS
wheel speed sen-
sor or magnetic
encoder as a unit
with hub unit bear-
ing if it is broken or
damaged.

Go to step 8.

CHECK ABSCM&H/U.
1) Connect all connectors.
2) Clear the memory. <Ref. to ABS(diag)-20,
Clear Memory Mode.>
3) Perform the Inspection Mode. <Ref. to
ABS(diag)-19, Inspection Mode.>
4) Read the DTC.

Is the same DTC displayed?

Replace the
ABSCM only. <Ref.
to ABS-8,
REPLACEMENT,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

Go to step 9.

ABS(diag)-40

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

J: DTC C0120 FRONT INLET SOLENOID VALVE LH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

NOTE:
Refer to DTC C0126 for diagnostic procedure. <Ref. to ABS(diag)-41, DTC C0126 REAR INLET SOLENOID
VALVE RH MALFUNCTION IN ABS CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/
U), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

K: DTC C0122 FRONT INLET SOLENOID VALVE RH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

L: DTC C0124 REAR INLET SOLENOID VALVE LH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
ABS(diag)-29, List
of Diagnostic Trou-
ble Code (DTC).>

It results from a
temporary noise
interference.

NOTE:
Though the ABS
warning light re-
mains on at this
time, this is normal.
Drive the vehicle at
12 km/h (7 MPH)
or more in order to
turn ABS warning
light off. Be sure to
drive the vehicle
and check that the
warning light goes
off.

Step

Check

Yes

ABS(diag)-41

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

M: DTC C0126 REAR INLET SOLENOID VALVE RH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

DTC DETECTING CONDITION:
• Defective harness connector
• Defective inlet solenoid valve in ABSCM&H/U
TROUBLE SYMPTOM:
• ABS does not operate.
• EBD does not operate.

NOTE:
Brake warning light illuminates as well as the ABS warning light.
WIRING DIAGRAM:

ABS00805

MAIN SBF

SBF-6

No.33

B301

ABSCM & H/U

BATTERY

GENERATOR

IGNITION
SWITCH

B301

1 2 3 4 5 6 7 8 9 10 11

16 17 18 19 20 21 22 23 24 25 26

ABS(diag)-42

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

N: DTC C0121 FRONT OUTLET SOLENOID VALVE LH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

NOTE:
Refer to DTC C0127 for diagnostic procedure. <Ref. to ABS(diag)-43, DTC C0127 REAR OUTLET SOLE-
NOID VALVE RH MALFUNCTION IN ABS CONTROL MODULE AND HYDRAULIC CONTROL UNIT (AB-
SCM&H/U), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

O: DTC C0123 FRONT OUTLET SOLENOID VALVE RH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

P: DTC C0125 REAR OUTLET SOLENOID VALVE LH MALFUNCTION IN ABS

CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM&H/U)

Step

Check

Yes

CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Turn the ignition switch to OFF.
2) Disconnect the ABSCM&H/U connectors.
3) Run the engine at idle.
4) Measure the voltage between ABSCM&H/U
connector and chassis ground.

Connector & terminal

(B301) No. 18 (+) — Chassis ground (–):

Is the voltage 10 — 15 V?

Go to step 2.

Repair the
ABSCM&H/U
power circuit.

CHECK THE ABSCM&H/U GROUND CIR-
CUIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance between the
ABSCM&H/U connector and chassis ground.

Connector & terminal

(B301) No. 15 — Chassis ground:

Is the resistance less than 0.5

:? Go to step 3.

Repair the
ABSCM&H/U
ground harness.

CHECK POOR CONTACT IN CONNECTOR.

Is there poor contact in connec-
tor between generator, battery
and ABSCM&H/U?

Repair the connec-
tor.

Go to step 4.

Is the same DTC displayed?

Replace the
ABSCM&H/U.
<Ref. to ABS-6,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

Go to step 5.

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
ABS(diag)-29, List
of Diagnostic Trou-
ble Code (DTC).>

Temporary poor
contact occurs.

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